A virtual local area network (LAN) or “VLAN” is a logical subdivision of a Layer 2 network that makes a single Layer 2 infrastructure operate as though it were multiple, separate Layer 2 networks. This is accomplished by adding a numeric tag field (e.g., a VLAN tag) to each data packet as it leaves a Layer 2 switch which identifies the VLAN number to which the packet belongs. Other VLAN-enabled switches honor the VLAN numbering scheme to segregate the network into logical, virtual networks.
Current engineering standards for both IPv6 (Internet Protocol version 6) and Ethernet frame formats place a VLAN tag packet or bytes outside the IPv6 payload. A commonly-accepted protocol used in configuring VLANs is IEEE 802.1Q, which defines a 32-bit long VLAN tag header. One disadvantage of Ethernet frame formats for VLANs, however, is that the VLAN tag headers add additional bandwidth overhead to network communications.